This application is based on and claims priority under 35 U.S.C. xc2xa7119 with respect to Japanese Patent Application 2000-303533, filed on Oct. 3, 2000, the entire content of which is incorporated herein by reference.
1. Field of the Invention
This invention generally relates to a control device which is applied in a synchromesh-type transmission for a vehicle. More particularly, this present invention pertains to a control device which is applied in a synchromesh-type transmission provided with a sleeve activated by a shift actuator in response to a shift operation. This invention further relates to a control device which controls operation of a shift actuator.
2. Background of the Invention
Vehicles such as passenger cars, buses and the like are generally driven by a driving power source such as a gasoline engine or an electric motor. The vehicle is provided with a transmission for producing a preferable vehicle driving condition in response to a vehicle running road condition. The transmission is for selecting gears, for meshing the selected gears with each other, and for changing the gears to be selected, to generate a desired torque or speed. As is well known, transmission types include a manual transmission (MT) and an automatic transmission (AT) in which a speed-change gear and a timing of speed-change are automatically selected.
As shown in FIG. 7, a known manual transmission (MT) is mainly formed as an input shaft 51, a plurality of counter gears 52, an output shaft 53, a plurality of idle gears 61, and a synchromesh mechanism 55 including a sleeve 56. The input shaft 51 is supplied with driving force from the driving power source such as the gasoline engine. The plurality of counter gears 52, are mounted on the input shaft 51. The output shaft 53 outputs driving force to vehicle wheels (not shown) via a propeller shaft (not shown). The plurality of idle gears 61 are idly mounted on the output shaft 53 and always meshes with the counter gears 52, respectively.
According to the vehicle provided with the known manual transmission, a predetermined speed-change gear is selected based on a manual shift operation by a driver. As shown in FIG. 8, upon the manual shift operation of a shift lever (not shown) by the driver, a shift fork shaft 67 (shown in FIG. 8) is moved by a shift operating force transmitted from the shift lever via a cable. Further, corresponding to the movement of the shift fork shaft 67, the sleeve 56 is moved, wherein one of the idle gears 61 meshes with the output shaft 53 as a unit.
Somewhat recent developments have led to an automatic manual transmissions which are structurally based on the manual transmission (MT). As shown in FIG. 8, the automatic manual transmission performs the shift operation by a shift actuator 65 which is made of, for example, a hydraulic pressure motor or a hydraulic pressure cylinder. Therefore, the automatic manual transmission effectively relieves a manual operating load from the diver. The shift lever (not shown) is operated to transmit the driver""s intention of speed-change and a timing of speed-change to an electronic control unit ECU 66. The ECU 66 controls the timing and the amount to activate the shift actuator 65.
The output from the shift actuator 65 is transmitted to the shift fork shaft 67 via a driving portion 65a (an output shaft of the shift actuator 65) and a shift fork shaft operating device 68 (formed as an inner lever, an interlock plate, and a shift head). Immediately after the shift actuator 65 is activated, the shift fork shaft 67 is axially moved via the shift fork shaft operating device 68. The sleeve 56 is integrally moved with the shift fork shaft 67 by an engagement between a projecting portion 67a of the shift fork shaft 67 and an engaging groove 56a defined in the sleeve 56,
According to the known aforementioned automatic manual transmission, when the shift fork shaft 67 and the sleeve 56 are moved by the output from the shift actuator 65 via the shift fork shaft operating device 68 upon a synchronizing operation being performed, it is very important to determine the amount of driving force the shift actuator 65 applied to the sleeve 56. More specifically, as shown in FIG. 7, the sleeve 56 is meshed with splines defined in a synchronizer hub 57. The synchronizer hub 57 is rotated integrally with the output shaft 53. When the driving force is applied to the sleeve 56, a synchronizer key 58 is engaged with the sleeve 56 and moved therewith. An edge surface of the synchronizer key 58 pushes a synchronizer ring 59 against a cone portion of the idle gear 61. Accordingly, the rotation of the idle gear 61 is gradually synchronized with the rotation of the sleeve 56.
According to further movement of the sleeve 56, the sleeve 56 is disengaged from the synchronizer key 58 and directly pushes the synchronizer ring 59. The rotational speed of the idle gear 61 becomes equal to the rotational speed of the sleeve 56 due to frictional engagement between the synchronizer ring 59 and the idle gear 61, i.e. the idle gear 61 is synchronized with the sleeve 56. Hereinafter, the synchronizer ring 59 is rotated independently and does not hinder the sleeve 56 from moving. Therefore, the sleeve 56 passes through the synchronizer ring 59 and is engaged with the idle gear 61, wherein the shift operation is completed.
If the driving force transmitted from the shift fork shaft 67 to the sleeve 56 is far larger than a desired amount, the synchronizer ring 59 and/or an inclined surface of the cone portion of the idle gear 61 may be damaged due to excess friction, thereby deteriorating durability of the idle gear. On the other hand, if the driving force transmitted from the shift fork shaft 67 to the sleeve 56 is far smaller than the desired amount, more time is required to perform the synchronizing operation between the sleeve 56 and the idle gear 61. Furthermore, a reliable synchronizing operation may not occur. To overcome the aforementioned drawbacks, the amount of the driving force applied to the sleeve 56 via the shift fork shaft 67 has to be effectively controlled by the shift actuator 65, so that the synchromesh mechanism 55 may operate with higher durability and with a shorter synchronizing time.
In view of the above, according to the known automatic manual transmission, a load detecting sensor 63 is mounted on the sleeve 56 as shown in FIG. 8. The load detecting sensor 63 detects the driving force applied to the sleeve 56. The detected value by the load detecting sensor 63 is transmitted to the ECU 66, so that the driving force from the shift actuator 65 is controlled based on the detected value. However, extra time may be required for installing the sensor 63 and an extra load may be placed on the sleeve 56. Further, manufacturing cost will increase for mounting the load detecting sensor 63 on the sleeve 56.
According to the known automatic manual transmission, an output indicating value which is input to the shift actuator 65 is detected. If the shift actuator 65 is made of a hydraulic pressure motor, the output indicating value is an electric current value supplied to a coil. If the shift actuator 65 is made of a hydraulic pressure cylinder, the output indicating value is an electric current value supplied to a solenoid valve. However, even when the output indicating value is properly detected, a desired driving force may not be generated by only detecting the output indicating value, due to resistance and friction within the shift actuator 65. Therefore, in addition to the detection of the output indicating value, a rotational number of a rotating portion of the hydraulic pressure motor or a stroke of a piston included in the hydraulic pressure cylinder is detected. However, it may be difficult to detect the output indicating value and to detect the rotational number of the hydraulic pressure motor or the stroke of the piston included in the hydraulic pressure cylinder.
As described above, certain improvements are desirable for the above known automatic manual transmission for the vehicle such as providing an improved control device applied in a synchromesh-type transmission that can determine the driving force applied from the shift actuator 65 to the sleeve 56 without detecting the actual driving force by a load detecting sensor 63 and the like in order to reduce manufacturing time and cost while not causing damage to the synchromesh mechanism 55.
A transmission system, including a synchromesh-type transmission, includes a) an input shaft rotated corresponding to driving power from a driving power source, b) an idle gear mounted on the input shaft, c) an output shaft applied with the driving power from the input shaft, d) a counter gear mounted on the output shaft and meshed with the idle gear, e) a sleeve rotated with the input shaft and moved in an axial direction of the input shaft, f) a synchromesh mechanism for selecting a predetermined speed-change in response to a synchronizing operation of the sleeve and the idle gear, and g) a shift actuator for activating the sleeve depending on a shift operation. The transmission system further includes h) a detecting means for detecting an angular speed or an angular acceleration of the input shaft when a synchronizing operation is performed in accordance with an engaging operation of the sleeve and the idle gear and i) a controlling means for controlling an operation of the shift actuator depending on an indication from the detecting means. The transmission system further includes a converting means for converting an output indicating value to the shift actuator based on characteristics of the shift actuator.